Rename branch `master` to `main`

[stevepiercy]

Reference: #623 (comment)

[niccokunzmann]

• This also needs adjusting the documentation and the README
• The test cases should work.
• We will see if the changelog tester will pick this up
• Make sure readthedocs builds for main

Github might have a way to rename the branch.

[stevepiercy]

Github might have a way to rename the branch.

Yup.

https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-branches-in-your-repository/renaming-a-branch

[niccokunzmann]

This is recommended to update your local clone:

git branch -m master main
git fetch origin
git branch -u origin/main main
git remote set-head origin -a

[niccokunzmann]

I adjusted readthedocs, too.

[niccokunzmann]

It seems all conditions for closing this are met. If you witness anything off, please reopen or report in a new issue.